cli: --disk: Don't try to detect path opt collisions

The checking is hard to get right because there are many ways to
specify storage. Rework it to try to determine if we should
create storage from disk XML contents

virtinst/cli.py

@@ -2799,7 +2799,6 @@ class ParserDisk(VirtCLIParser):
             else:
                 fail(_("Unknown '%s' value '%s'") % ("perms", val))
 
-        has_path = "path" in self.optdict
         backing_store = self.optdict.pop("backing_store", None)
         backing_format = self.optdict.pop("backing_format", None)
         poolname = self.optdict.pop("pool", None)
@@ -2808,17 +2807,6 @@ class ParserDisk(VirtCLIParser):
         fmt = self.optdict.pop("format", None)
         sparse = _on_off_convert("sparse", self.optdict.pop("sparse", "yes"))
         convert_perms(self.optdict.pop("perms", None))
-        has_type_volume = ("source_pool" in self.optdict or
-                           "source_volume" in self.optdict)
-        has_type_network = ("source_protocol" in self.optdict)
-
-        optcount = sum([bool(p) for p in [has_path, poolname, volname,
-                                          has_type_volume, has_type_network]])
-        if optcount > 1:
-            fail(_("Cannot specify more than 1 storage path"))
-        if optcount == 0 and size:
-            # Saw something like --disk size=X, have it imply pool=default
-            poolname = "default"
 
         if volname:
             if volname.count("/") != 1:
@@ -2830,6 +2818,14 @@ class ParserDisk(VirtCLIParser):
 
         super()._parse(inst)
 
+        if (size and
+            not volname and
+            not poolname and
+            not inst.path and
+            inst.type == inst.TYPE_FILE):
+            # Saw something like --disk size=X, have it imply pool=default
+            poolname = "default"
+
         # Generate and fill in the disk source info
         newvolname = None
         poolobj = None